This invention relates to apparatus for selectively communicating therethrough fluid from one of a plurality of sources. More particularly, it relates to a low pressure selector for communicating therethrough fluid from the lower pressure source of a plurality of pressure sources.
In vehicle pneumatic braking systems, it is desirable to monitor supply pressure available for braking usage to detect any condition in which supply pressure falls to an unacceptable level. Low pressure responsive monitors have been designed for monitoring pressure in such systems which, until recently, have generally employed a unitary source of supply pressure. Such low pressure responsive monitors typically warn the operator of the vehicle of a reduction in pressure by dropping a warning flag into the operator's view. One such low pressure responsive monitor is the Automatic Low-Pressure Signal monitor, Part No. 920, manufactured by The Berg Manufacturing Company, a Division of The Echlin Manufacturing Company.
In recent years, however, vehicle pneumatic braking systems have been developed which employ two sources of supply pressure. Monitoring pressure in such systems can be accomplished by employing two low pressure responsive monitors, each connected to one of the sources. Such use of two monitors may be expensive, however, and presents difficulties in the placement and mounting of the additional monitor. Consequently, it is desirable to obviate the duplication of monitors required by the aforementioned arrangement and the costs and installation problems attendant such duplication. This invention is directed to a low pressure indicator apparatus wherein a novel low pressure selector communicates fluid from the lower pressure source of a plurality of pressure sources to a low pressure responsive monitor.